void hook_config_section(const char *section, int (*intgetter)(const char *name, int def), const char *(*stringgetter)(const char *name, const char *def), void (*stringsetter)(const char *name, const char *value));
   int decode_encrypted_int(const char *name, int def)
   {
      ...
   }
   
   const char *decode_encrypted_string(const char *name, const char *def)
   {
      ...
   }
   
   void encode_plaintext_string(const char *name, const char *value)
   {
      ...
   }
   
   int main(int argc, char *argv[])
   {
      ...
      /* Make it harder for users to tinker with the high scores. */
      hook_config_section("high_scores", decode_encrypted_int,
         decode_encrypted_string, encode_plaintext_string);
      ...
   } END_OF_MAIN()